1. Field of the Invention
The invention relates to a method for milling a blank in the production of a turbine blade which in the final state has at least one blade root for fastening to a carrier and also a blade body adjoining the blade root and extending in the longitudinal direction.
2. Background Information
Owing to the high thermal and mechanical loading which they must withstand, turbine blades consist of so-called superalloys. These are generally characterized by a very high strength, for example of >1000 N/mm2, and a high temperature resistance. Tools, in particular milling tools for machining such superalloys, are therefore usually subject to a high degree of wear. Moreover, the machining rate is substantially reduced by comparison with softer steels.
To produce such turbine blades, which have a blade root for hooking into a carrier, a monolithic blank, that is to say a workpiece block which usually has an approximately parallelepipedal shape, is subjected to a milling operation.
The blade body of the turbine blade usually has, when viewed in cross section, an approximately aerofoil-like contour. EP 1 034 865 A1 discloses a milling method for machining a blank in which the milling cutter is guided in an approximately spiral shape around the blank and thus removes the successive material until the desired final contour is achieved. The machining time in this method is comparatively high.
Hence there is room for improvement in methods for machining turbine blades.